This invention relates generally to vehicle transfer cases having a plurality of outputs and more particularly to an automatic power transfer case providing full time four wheel drive.
It is known to provide vehicle transfer cases having full time four wheel drive capabilities which utilize manual shifting. An example of such a transfer case is found in U.S. Pat. No. 4,677,873 issued Jul. 7, 1987 to R.E. Eastman et al. entitled Transfer Case With Inter-Axle Dual-Planetary Differential.
The U.S. Pat. No. 3,845,671 issued Nov. 5, 1974 to E.A. Sharp et al. discloses a slip controlled four wheel drive train including a transfer case adapted to provide full time four wheel drive. A differential is provided in the transfer case which is electrically controlled to be locked to prevent differentiation when slip between the input and output shafts exceed a predetermined tolerance.
The U.S. Pat. No. 4,644,822 issued Feb. 24, 1987 to R. B. Batchelor discloses a transfer case for vehicle drivetrains having back-to-back first and second planetary gear sets.
The U.S. Pat. No. 4,690,015 issued Sept. 1, 1987 to Nagano et al. discloses a power transfer device for automotive vehicles.
The U.S. Pat. No. 4,711,136 issued Dec. 8, 1987 to Yoshinaka et al. discloses a power transfer device for four-wheel drive vehicles.